Process for defecating sugar juice



Patented Mar. d, 192%.

mam

WILLIAM DODGE HORNE, OF YONKERS, NEW YORK.

PROCESS FDR DEFECATING SUGAR JUICE.

fi o Drawing.

To all whom it may concern:

Be it known that 1, WILLIAM Dooon HORNE, a citizen of the United States,and a resident of the city of Yonkers county of S \Vestchester, andState of New York, have invented a new and Improved Process forDefecating Sugar Juice, lowing is a full, clear, and exact description.

This invention relates to a process for the w defecating of sugar juiceand hasreference more particularly to a process of the class described,in which the sugar juice is first treated with lime to strongalkalinity. to litmus and after the removal of the precipi- 1 tateformed, a precipitant such as sodium phosphate is added to precipitatethe excess of lime. v

Acomplete precipitation .of the precipitable impurities in cane. juicecan only 29 attained by adding lime considerably beyond the point of aslight alkalinity to lit-. mus, but it is not always'necessa'ry to addlime to the point of alkalinity to phenolphthalein. The exact amount'maybe de- $5 termined by experiment by testing the filtrate from anyparticular lime addition with more lime andheating to see if a vfurtherprecipitate is thrown down. In the case of burnt, fermented or unusuallyacid sugar so juice, soda, such as the hydroxide, carbonate orbicarbonate of sodium, may be added to make the precipitation more comlete. Only a moderate heat, 105450 degrees is necessary to complete theprecipitation. e-

ficiency' of lime cannot be made up for by excessive heating. Thepractice heretofore has been to heat the sugar solution to 200 F. orover, after adding a quantity of lime which would not destroy the invertsugar at 40 the high temperature. owever, this quantity is insuflicientto precipitate all the impurities in the sugar solution. In any eventthe solution must be strongly alkaline to I litmus to insure theinsolubility of the precipitate formed;

Any appreciable amount of lime leftin a sugar solution is verydetrimental, as in the heatin of thet solution to evaporate and crystalize, the lime combines chemically 5a with the reducing sugars, formingdarkcol-v of which the fol- Application flied November 13,1919. SerialNo. 387,823.

ored bodies which cannot be removed by crystallization, but remain insolution and prevent thecrystallization of sugar. Therefore in anysatisfactory method of defecation some means must be provided forremoving that portion of the added lime whichis not precipitated by theacids, gummy substances, nitrogenous bodies, etc.,' in the raw juice. Ifthe excess of lime over that existing .in the precipitate be neutralizedwith phosphoric acid alone or a phosphate acid to litmus in the presenceof the precipitate, the precipitate will immediately redissolve in largepart, allowing the once separated impurities again-t0 enter intosolution and so defeat'the object of. the defecation.)

The object ofthis invention therefore is to filter, settle out, or floatoff the precipitated impurities, resulting from the addiof large amountstion of lime, from the clarified juice, and

then to remove the excess of lime so as to prevent the subsequentdestruction of reduc:

ing sugars, formation of dark colored melassigenic substances, formationoi lime scales on the heating tubes and surfaces of the heatingappliances, slow boiling, cloudy residual molasses, and a strongdisagreeable taste in the-final sugar products.

The removal of the excess of lime is best accomplished by the additionof sufficient suitable lime precipitant, such as a soluble phosphate,carbonate, bicarbonate, sulphite, isulphite, oxalate, 'etc., preferablyneutral or slightly alkaline to litmus, at a tempera-- ture of 175 F. orabove. Phosphoric acid alone .or a is not suita le for this purpose. assuch rea ent is far from thorough in its removal 0 lime. However, saidphosphoric acid or acid phosphate may be mixed with the properproportion of theoxide, hydrate, carbonate, and (or) bicarbonate ofsodium, and on adding this mixture to the sugar-5 containing liquid, thelime. is practically phosphate, acid to litmus alone thoroughlyprecipitated. Themore basic soluble phosphate, etc., is far moreefiicie'nt in its'lime removing power than phosphoric acid or a hosphateacid to litmus. A solue ble phosp ateofsoda-mfly be used to m cipitatethe excess lime, and very good results are obtained thereby. Such asoluble phosphate or equivalent isadded in correct proportion,determined or checked, by experiment, and the solution is then heated tonear the boiling point with safety, as neither sugar nor reducingv sugaris destroyed nor attacked, but the lime is almost table by lime.

completely precipitated immediately as an insoluble phosphate. or othercompound. The separate ingredients for forming any of these precipitantsmay be' added separately to the juice with equally good effect. Theresulting precipitate settles Very quickly in the solution, leaving itbright and clear as well as very light colored and suitable for makingthe very best grade of raw sugar or even a sugar for direct consumption.This second precipitation, with a phosphate neutral or alkaline tolitmus, further removes the iron from the juice, which greatly improvesthe latter for making either direct consumption sugars or raw sugars forrefining. It removes also the small pieces of cane fibre or bagasillowhich escape the first efiort at clarification and which if left in thejuice find .their way into the raw sugar, where they retain theirmoisture and become centers of infection by micro-organisms whichferment the sugar and cause large deterioration losses in storage andtransportation.

'The precipitation with the llme and with the phosphate can be easilycarried out without any special machinery or appliances as thesedimentations may take place in ordinary tanks.

The two precipitates, settled from their respective solutions, afteronce diluting and ecanting, may be combined and filterpressed. Theefiicient fertilizer as it contains practically all of the nitrogenousmatter of the raw juice and-all the phosphatic matter of the defecant.This hosphatic matter, further, is nearly all in t e form immediatelyavailable to plants as food, and the littlethat may not be immediatelyavailable will gradually become available in the'soil.

To the fresh cold cane juice, milk of lime or dry lime is added bebeyond the point of alkalinity to litmus and sutficient to precipitatecompletely all those substances precipi- This' will be about 030% or040% lime on the Weight of the juice. An average juice is acid andrequires 02% lime to neutralize to litmus and .0a% lime to neutralize tophenol phthalein. It will require about 03% ,to 04% lime to precipitatefully all the precipitable matters. 'lhis limed juice is heated inLouisiana to about 105 F. to efiect complete precipitation; in Porto.Rico to about 150 18. At these moderate temperatures no invert sugar isdestroyed. The juiee is settled and the clear press cake may be used asanjuice decanted or the juice is filtered. To the clear juice'is nowadded about 02% of actual acid calcium phosphate and enough sodiumcarbonate to insure a neutral or approximately neutral reaction tolitmus in the sugar solution. Part of the acid phosphate precipitatesthe free lime and the remainder reacts with the sodium carbonate toproduce phosphate of soda, which immediately combines with the lime ofthe dissolved lime salts in the solution, precipitating this lime. Theamount of this sodium carbonate is about one-third of the acid phosphateused. Phosphoric acid can be used as a substitute for acid phosphate oflime; so also may one employ phosphate of soda directly instead offorming it in the sugar solution. After adding these re-agents thetemperature is spirit of the invention as defined in the appendedclaims.

Having thus described my invention, 1 claim as new and desire to secureby Letters Patent z- 1. A process for defecating sugar containingliquids which consists in adding to said liquids sufficient lime to givea complete precipitation of all substances precipitable by lime and toimpart a strong alkalinity to the sugar containing liquid, maintainingsaid liquid at a temperature ranging from F. to 150 F, separating theprecipitate, subjecting the solution of strong alkalinity to the actionof a mixture of phosphoric acid and sodium carbonate to pre cipitateboth the free lime'and the lime contamed therein in the form ofdissolved lime salts, and then raising the temperature of the liquid toa point above 150 l. to facilitate the last mentioned reactions.

2. A. process for defecating sugar contaming liquid which consists inadding to said liquid sufiicient lime to give a complete precipitationof all substances'precipitable by lime and leave the liquid in a stateof strong alkalinity, maintaining said liquid at a degree of temperaturebetween 105 F. and 150 F, and separating the precipitate, sub ecting thesolution of strong alkalinity to the action of a mixture of an aciphosphate and a sodium salt to precipitate both the free lime and thelime remaining in the liquid in. the form of dissolved lime salts, thelast mentioned reaction being carried out at a dgree of temperature inexcess of 150 F.

3. A process for defecating sugar containtion of a. mixture ofphosphoric acid and ing liquids which comprises adding to said sodiumcarbonate to precipitate the free liquid .03% to 04% of lime to causeprelime in solution and the lime contained in 10 cipitation of matter inthe liquid and impart said solution in the form ofldissolved lime n astrong alkalinity to the'sugar containing salts, and raising'thetemperature of the liquid, separating the precipitate subjectingsolution in excess of 150 F. the solution of strong alkalinity to theac- WILLIAM DODGE HORNE.

